360 research outputs found
Minimal Neutrino Beta Beam for Large theta_13
We discuss the minimum requirements for a neutrino beta beam if theta_13 is
discovered by an upcoming reactor experiment, such as Double Chooz or Daya Bay.
We require that both neutrino mass hierarchy and leptonic CP violation can be
measured to competitive precisions with a single-baseline experiment in the
entire remaining theta_13 range. We find that for very high isotope production
rates, such as they might be possible using a production ring, a (B,Li) beta
beam with a gamma as low as 60 could already be sufficient to perform all of
these measurements. If only the often used nominal source luminosities can be
achieved, for example, a (Ne,He) beta beam from Fermilab to a possibly existing
water Cherenkov detector at Homestake with gamma \sim 190-350 (depending on the
Double Chooz best-fit) could outperform practically any other beam technology
including wide-band beam and neutrino factory.Comment: 11 pages, 2 figures, 1 tabl
Resolving the octant of theta23 with T2K and NOvA
Preliminary results of MINOS experiment indicate that theta23 is not maximal.
Global fits to world neutrino data suggest two nearly degenerate solutions for
theta23: one in the lower octant (LO: theta23 < 45 degree) and the other in the
higher octant (HO: theta23 > 45 degree). numu to nue oscillations in superbeam
experiments are sensitive to the octant and are capable of resolving this
degeneracy. We study the prospects of this resolution by the current T2K and
upcoming NOvA experiments. Because of the hierarchy-deltacp degeneracy and the
octant-deltacp degeneracy, the impact of hierarchy on octant resolution has to
be taken into account. As in the case of hierarchy determination, there exist
favorable (unfavorable) values of deltacp for which octant resolution is easy
(challenging). However, for octant resolution the unfavorable deltacp values of
the neutrino data are favorable for the anti-neutrino data and vice-verse. This
is in contrast to the case of hierarchy determination. In this paper, we
compute the combined sensitivity of T2K and NOvA to resolve the octant
ambiguity. If sin^2\theta23 =0.41, then NOvA can rule out all the values of
theta23 in HO at 2 sigma C.L., irrespective of the hierarchy and deltacp.
Addition of T2K data improves the octant sensitivity. If T2K were to have equal
neutrino and anti-neutrino runs of 2.5 years each, a 2 sigma resolution of the
octant becomes possible provided sin^2\theta23 \leq 0.43 or \geq 0.58 for any
value of deltacp.Comment: 27 pages, 38 pdf figures, 1 table. New figures are given in the
results section to show the octant discovery reach as a function of true
theta23 and true CP phase. Few changes in the abstract, results and
conclusions section to incorporate the new results. Published in JHE
In Defence of Future Generations: A Reply to Stephen Humphreys
In this reply to Stephen Humphreys, we challenge the dismissal of future generations as a locus of responsibility for present generations. Drawing from diverse sources such as indigenous law, environmental jurisprudence and practice, we demonstrate that global discourse on intergenerationality is broader and more nuanced than Humphreys suggests. Our response highlights the importance of incorporating diverse perspectives to enrich discourse and promote an inclusive approach to the progressive development of international law. Further, we contend that ‘future generations’ discourse has emancipatory power, offering potential for reshaping international law based on a vision of justice and solidarity across time and space. We call for increased dialogue and collaboration among scholars, practitioners and frontline communities to ensure that future generations discourse remains grounded in real-world experiences. By persistently interrogating and developing our understanding of responsibilities owed to future generations, we can imagine and cultivate a more inclusive – and, hence, more promising – approach to addressing climate change and related global crises
Neutrino parameters from matter effects in at long baselines
We show that the earth matter effects in the
survival probability can be used to cleanly determine the third leptonic mixing
angle and the sign of the atmospheric neutrino mass squared
difference, , using a -beam as a source.Comment: 4 pages, 4 eps figures; comments and references added, to appear in
Phys. Rev.
Thermal stabilization of thymidylate synthase by engineering two disulfide bridges across the dimer interface
Thermal inactivation of oligomeric enzymes is most often irreversible and is frequently accompanied by precipitation. We have engineered two symmetry related disulfide bridges (155-188′ and 188-155′) across the subunit interface of Lactobacillus casei thymidylate synthase, at sites chosen on the basis of an algorithm for the introduction of stereochemically unstrained bridges into proteins. In this communication, we demonstrate a remarkable enhancement in the thermal stability of the covalently cross-linked double disulfide containing dimeric enzyme. The mutant enzyme remains soluble and retains secondary structure even at 90°C, in contrast to the wild-type enzyme which precipitates at 52°C. Furthermore, the mutant enzyme has a temperature optimum of 55°C and possesses appreciable enzymatic activity at 65°C. Cooling restores complete activity, in the mutant protein, demonstrating reversible thermal unfolding. The results suggest that inter-subunit crosslinks can impart appreciable thermal stability in multimeric enzymes
Neutrino Mixings and Leptonic CP Violation from CKM Matrix and Majorana Phases
The high scale mixing unification hypothesis recently proposed by three of us
(R. N. M., M. K. P. and G. R.) states that if at the seesaw scale, the quark
and lepton mixing matrices are equal then for quasi-degenerate neutrinos,
radiative corrections can lead to large solar and atmospheric mixings and small
reactor angle at the weak scale in agreement with data. Evidence for
quasi-degenerate neutrinos could, within this framework, be interpreted as a
sign of quark-lepton unification at high scale. In the current work, we extend
this model to show that the hypothesis works quite successfully in the presence
of CP violating phases (which were set to zero in the first paper). In the case
where the PMNS matrix is identical to the CKM matrix at the seesaw scale, with
a Dirac phase but no Majorana phase, the low energy Dirac phase is predicted to
be () and leptonic CP-violation parameter and . If on the other hand, the
PMNS matrix is assumed to also have Majorana phases initially, the resulting
theory damps radiative magnification phenomenon for a large range of parameters
but nevertheless has enough parameter space to give the two necessary large
neutrino mixing angles. In this case, one has and as large as which are accessible to long
baseline neutrino oscillation experiments.Comment: 15 pages and 10 figures, typo correcte
Precision on leptonic mixing parameters at future neutrino oscillation experiments
We perform a comparison of the different future neutrino oscillation
experiments based on the achievable precision in the determination of the
fundamental parameters theta_{13} and the CP phase, delta, assuming that
theta_{13} is in the range indicated by the recent Daya Bay measurement. We
study the non-trivial dependence of the error on delta on its true value. When
matter effects are small, the largest error is found at the points where CP
violation is maximal, and the smallest at the CP conserving points. The
situation is different when matter effects are sizable. As a result of this
effect, the comparison of the physics reach of different experiments on the
basis of the CP discovery potential, as usually done, can be misleading. We
have compared various proposed super-beam, beta-beam and neutrino factory
setups on the basis of the relative precision of theta_{13} and the error on
delta. Neutrino factories, both high-energy or low-energy, outperform
alternative beam technologies. An ultimate precision on theta_{13} below 3% and
an error on delta of < 7^{\circ} at 1 sigma (1 d.o.f.) can be obtained at a
neutrino factory.Comment: Minor changes, matches version accepted in JHEP. 30 pages, 9 figure
A minimal Beta Beam with high-Q ions to address CP violation in the leptonic sector
In this paper we consider a Beta Beam setup that tries to leverage at most
existing European facilities: i.e. a setup that takes advantage of facilities
at CERN to boost high-Q ions (8Li and 8B) aiming at a far detector located at L
= 732 Km in the Gran Sasso Underground Laboratory. The average neutrino energy
for 8Li and 8B ions boosted at \gamma ~ 100 is in the range E_\nu = [1,2] GeV,
high enough to use a large iron detector of the MINOS type at the far site. We
perform, then, a study of the neutrino and antineutrino fluxes needed to
measure a CP-violating phase delta in a significant part of the parameter
space. In particular, for theta_13 > 3 deg, if an antineutrino flux of 3 10^19
useful 8Li decays per year is achievable, we find that delta can be measured in
60% of the parameter space with 6 10^18 useful 8B decays per year.Comment: 19 pages, 10 figures, added references and corrected typo
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